With great amount of unsaturated double bonds, non-hydrogenated conjugated diene polymers, such as copolymer/homopolymer of butadiene or isoprene or block/non-block copolymer of styrene-butadiene/isoprene, are usually advantageously applicable in crosslinking reactions like functionalization, grafting and vulcanization, etc. However, non-hydrogenated conjugated diene polymer is very unstable as being prone to degradation due to heat or oxidation in exposed of ultra-violet light or other unfavorable environment. Since that, in practice, those non-hydrogenated copolymers are improved by appropriate hydrogenation to largely reduce the amount of the unsaturated double bonds, so as to get good properties against unfavorable environment. Conventionally, catalysts used for hydrogenation of the conjugated diene polymer are classified into two types, heterogeneous catalysts and homogenous catalysts, wherein the homogeneous one has relatively higher activities by which the reaction can be conducted at mild pressure and temperature.
European Patent Appl. No. 2316862 discloses a method for hydrogenating the conjugated diene polymer in homogenous system using a catalyst composition containing a titanium compound and a fully substituted silane, wherein the fully substituted silane catalyst stabilizes other catalyst components in the catalyst composition and therefore enhances the catalytic activity. However, such catalyst composition still has shortcomings in its application. Therefore, there is a need to provide a new catalyst composition to fit the application requirements.